COT Spectacle Dispensing and Frame Fitting

Question 1

When measuring monocular pupillary distances (PDs) for a progressive addition lens prescription, the technician measures the distance from the center of each pupil to:

Accepted Answer

The center of the nose bridge (midline)

Answer

Monocular PD is measured from the center of each pupil to the midline (center of the nose). This gives a right PD and a left PD separately, which is critical for progressive lenses where optical centers must be precisely aligned to each pupil independently.

Question 2

Pantoscopic tilt of a spectacle frame refers to:

Accepted Answer

The vertical forward tilt of the lens plane, with the bottom of the lenses closer to the cheeks than the top

Answer

Pantoscopic tilt is the vertical angle of the spectacle lens plane relative to the face — ideally 8–12° — with the lower edge of the lenses tilted toward the cheeks. This aligns the optical axis of the lens with the natural downward gaze direction used for reading.

Question 3

Vertex distance becomes clinically significant when a patient's spectacle prescription exceeds approximately:

Accepted Answer

±4.00 D

Answer

Vertex distance (the distance from the back surface of the spectacle lens to the front of the cornea) must be accounted for in prescriptions of approximately ±4.00 D or greater. At higher powers, even a few millimeters of difference in vertex distance changes the effective power of the lens reaching the eye.

Question 4

A patient's new glasses sit too close to the eyelashes, causing discomfort. The correct adjustment to increase the distance between the lenses and the eyes is to:

Accepted Answer

Open the nose pads outward to push the frame away from the face

Answer

Adjusting the nose pads outward (increasing the pad spread) raises the frame higher and pushes it away from the face, increasing vertex distance and reducing contact with the eyelashes. This is the appropriate frame adjustment for glasses sitting too close to the eyes.

Question 5

When fitting a patient for spectacles, the correct temple length provides support by:

Accepted Answer

Bending at the ear level and resting on the mastoid bone behind the ear

Answer

A properly fitted temple should bend at approximately the level of the top of the ear and rest along the side of the head, with the temple tip resting behind and below the ear on the mastoid area. This distributes weight properly and prevents the frame from sliding down.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Spectacle Dispensing and Frame Fitting